BEFORE BUILDING any RC
airplane, it is good to know why it
should be built. The SkyCruiser
was born in my imagination to fill a
need for a realistic-looking,
electric-powered, four-channel
airplane that is influenced by all of
Cessna’s famous single-engine
four-seaters. This is not a scale
model of a particular design—it is
my own design—but I like the
features on many airplanes I’ve seen.
The SkyCruiser was also designed with
ease of transport in mind. With a 48-inch
wingspan it will fit in my vehicle’s trunk
without my having to remove wings, and it
should fit in the backseat of any four-door
car if the trunk is not big enough.
This model takes advantage of one of the
great, new outrunner brushless electric
motors and the new Li-Poly batteries.
It can be launched by hand (for park
flying), but with the steerable nose
wheel and four-channel control it can
also be taken off from a smooth
runway.
My plans and construction article
include a fully detailed interior, which
you can leave out if you want to get
the SkyCruiser into the air sooner.
Let’s start building.
CONSTRUCTION
Before you build the model, use a scroll
saw to cut all the pieces that will be used to
May 2007 33
BY CLARK SALISBURY
With sporty lightplane
looks, this is a great first
built-up model project
The SkyCruiser looks wonderful from any angle in the air!
05sig2.QXD 3/23/07 1:18 PM Page 33
34 MODEL AVIATION
The completed wing panels are joined by clamping the front and rear plywood dihedral
joiners to the main spar. Be sure to check the dihedral angle.
The wing panel halves are built directly over the full-size plans. It’s hard to build a warp
into this wing!
The wing-mount pads have been added to the structure.
Fuselage construction begins by gluing 3/16 square balsa strips
adjacent to the edges of the fuselage sides.
pieces to the center-section and let the
structure dry before sanding each wheel
pant to its final shape.
Seat Bases: The optional seat bases are
made from 1-inch balsa block. Glue 3/16
balsa to both sides of the 1-inch block to
make it thick enough for the seat bases and
seat backs.
It is easiest if you cut the radius contour
and then cut out the side profile. Then cut
out the top profile. After doing that, you can
sand them with fine sandpaper, glue the seat
back to the seat pedestals, and then glue the
seat base in place.
Tail Feathers: The tail feathers are easy to
construct on a piece of drywall. T-pins stuck
into the drywall will hold everything
together while it’s drying. Be sure to use a
piece of waxed paper over the plans so the
wood won’t stick to them.
Hinges: Go ahead and install the hinges at
this point, slotting the balsa as shown on the
plans. A cutoff wheel on a Dremel tool
works well for making the slots. Don’t
epoxy the hinges yet.
Wing: You can build both wings at the
same time. You will need to space up the
LE balsa dowel exactly 3/16 inch; you can do
this with scrap 3/16 balsa. After you have
pinned the leading dowel, notch out the TE
for ribs 1-6.
Before gluing in ribs 1-5, lay the 1/16
plywood bottom spar piece, which goes
under the first five ribs. I added this piece to
my prototype afterward for strength, and it
will not be shown in the construction
photos. Pin it down and then glue ribs 1-6
on both wings.
Glue in ribs 7-9. But before you do you,
you will need to space up the TE of rib 9
with a scrap piece of 3/16 balsa.
Notch the 3/8 square balsa at the rear of
the ribs. You can sand it later to match the
ribs, or you could cut the angle on the top of
this piece with your scroll saw before you
glue in the ribs.
construct it. Adhere the plans to the wood
with a glue stick, noting the grain direction,
as shown on the plans.
Stack pieces of wood for components
that require more than one layer to build, as
indicated on the plans. When doing so, use a
tiny dab of glue on each corner to hold the
stack together.
Wheel Pants: The wheel pants are the first
items to construct. However, if your
SkyCruiser will be flying off of anything but
a smooth runway, I don’t recommend that
you build them. They are mostly for looks
and are fine if you can fly off of a smooth
runway with no big ruts or weeds.
For the wheel pants the plans call for 3/16
balsa stacked three high, with a layer of 1/16
balsa for the center-section of each. You can
stack all those layers for three wheel pants
and cut everything at the same time with a
scroll saw since the total thickness will be
17/8 inches.
You can stack the 1/16 pieces six high and
cut them for the outside of all three wheel
pants at the same time. Glue the outside
Photos by the author
05sig2.QXD 3/23/07 1:20 PM Page 34
May 2007 35
Bill of Materials
QUANTITY DESCRIPTION
Two packs 13/4-inch-diameter Hangar 9 Pro-Lite Wheels (item HAN 301)
One 36-inch-long, 1/16-inch-diameter steel rod
Two #6-32 x 1.5-inch screw (axle for rear wheels)
Nine #6 washers (spacers in wheel pants)
Two #6-32 nuts (to retain axles for rear wheels)
One Carl Goldberg 1/8 Nosegear Bearing (item 276)
One Carl Goldberg 1/8 Steering Arm, nylon (item 280)
One APC 9 x 6 electric composite propeller
One Du-Bro 11/2-inch spinner
One Graupner 4mm propeller adapter (item 286)
One Sig 1/8 x 13/4 nose-gear strut (item SIGSH596)
One PJS 3D 1000N brushless outrunner motor (www.czpjsza-motory.cz)
One ElectriFly SS-35 brushless ESC (item GPMM1830)
One Four-channel radio with four microservos (such as MPI MX-50s)
One Aileron Y harness (should be at least 12 inches long)
One Du-Bro 20-inch Micro Push Rod System (item 847)
One pack Du-Bro small nylon hinges (item 119)
Two packs Small control horns
One 12-inch #4-40 threaded rod (for aileron connection)
Four Small clevises for #4-40 rod (for aileron connection)
Two rolls Covering material (MonoKote or equivalent)
One bottle Aliphatic resin (Elmer’s wood glue)
One sheet 12 x 12-inch .020 acrylic clear sheet (for windshield)
Four 1-inch-long #10-32 nylon bolt (for wing attachment)
One 12 x 12-inch 1/16-inch-thick aluminum sheet (for landing gear)
One Three-cell Li-Poly battery, 1500 mAh minimum
Two 36-inch-long 1/4-inch-diameter balsa dowel
One 4-inch-long 3/16-inch-diameter hardwood dowel
Four 1/8 x 2 x 36 balsa strips
Two 3/32 x 6 x 36 balsa strips
One 3/16 x 2 x 36 balsa strip
Two 1/4 x 1 x 36 balsa TE
Two 3/16 x 3/8 x 36 balsa strips
Three 3/16 square x 36-inch balsa strip
One 1-inch-square x 36-inch balsa block
One 3/8 square x 18-inch balsa strip
Two 1/32 x 1 x 36 balsa strip
One 12 x 24 x 1/8 poplar plywood
One can Glossy spray paint (for wheel pants and seats)
One 1/4 oak or other hardwood piece measuring at least 1 x 4 inches
Glue in the wing spars. You can slide
the spars through the holes in the ribs, and
then rotate the spar into position and glue
all contact points.
It’s time to add the wingtips. Cut from a
1-inch balsa block using the pattern on the
plans for the left wingtip. Cut a mirror
image to make the right tip. The wingtips
are cut lengthwise at a 45° angle. When
gluing at the wingtips, the flat part of the
tip should be facing up.
Add the 1/32 balsa sheet to the wing LE
and hold with pins until the glue is dry.
Add the ailerons. Fit the hinges, but do not
glue them in place yet.
Remove the wing from the building
board to make the hinge slots, and sand the
entire wing before starting the next step.
The LE and the wingtips will require the
most sanding.
Install the front and rear dihedral
joiners to maintain the 4.5° dihedral angle.
Use the ailerons, which are exactly 1 inch
wide, to hold the dihedral angle, under rib
number 6, on both sides. Note that rib 1 to
rib 1 is exactly 33/8 inches, so draw two
lines on your building board to hold this
dimension.
Add wing mounts WM4, WM5, and
WM6 between the R1 wing ribs. Install the
33/8-inch-long piece of TE and a 33/8-inch
piece of 1/4-inch-diameter balsa dowel at
the front of the wing.
Install four scrap pieces (made from 1-
inch block) with 7/16-inch-diameter holes
above all four of the wing mounting holes.
After this dries, sheet the top of the wing
center with 1/32 balsa.
Fuselage: Begin fuselage construction by
laying 3/16 square balsa along the outer
edges of the fuselage sides (top and
bottom). This is so the entire fuselage can
be sanded to a 3/8-inch radius later and
have enough material.
As you lay in these square balsa pieces,
make sure they will be flush with the
bottom of all of the formers: F1-F8. You
will need to lay in the formers to determine
where this is, and draw lines between the
formers for locating the 3/16 balsa.
Glue in formers F2, F3, F4, and F6 to
only one side of the fuselage. These
formers should be perpendicular to the
fuselage side pieces, and you will need
something that holds them square.
Before you install former F4, mount the
motor, cover it with a sandwich bag, and
use an elastic piece to hold the bag on. I
didn’t do it this way, but the motor is
practically impossible to mount later. The
plastic bag is to protect the motor from
paint when you spray the front of the
fuselage later.
Glue in the other side of the fuselage
and add F7 and F8. Notice that the rear of
the fuselage is being held with one
clothespin and the front is held together
with elastics.
Add the top pieces of the fuselage and
the rear window. These components can be
held with T-pins and elastics.
05sig2.QXD 3/26/07 8:55 AM Page 35
The front cabin former, F4, is built as a separate assembly. The bent metal rod is epoxied
into the grooves.
The fuselage sides are joined with the top sheeting in place. The edges will be rounded
with a sanding block later.
Construct the optional removable front cover from scrap 1/4 balsa.
The front cabin former—F4—is built as
a separate assembly. The bent metal rod is
epoxied into the grooves, and the assembly
is held together with clothespins while it
cures. This assembly includes WM1.
Although it’s not shown, glue in the wing
mounts to the top of the cabin area—WM2
and WM3—along with the entire front
former assembly you built earlier.
Install the nose-gear bearing on F3. Glue
the F1 front nose piece in place and
construct the optional removable front cover
from scrap 1/4 balsa. This piece is
unnecessary for flight, but it does improve
the finished model’s realistic looks.
Glue in two 1/4 oak pieces and hold them
in place with clothespins. These pieces are
required only to attach the removable front
cover. The front cover can be held in place
with small wood screws going into the oak.
This front cover is not detailed in the plans,
but it will require sanding to match the front
fuselage’s profile.
Install the rear under-fuselage balsa
piece and hold it in place with pins to dry.
Add the F5 former, which will support the
servo tray. Make sure you install the servo
tray at a height that will work with your
servos and the minipushrods going to the
elevator and rudder.
Carefully sand the fuselage. This is
perhaps the most important operation on the
fuselage. Sand a 3/8-inch radius along the
entire bottom of the fuselage and then along
the top except where the wing will attach.
Type: RC sport
Wingspan: 48 inches
Wing area: 403 square inches
Flying weight: 34 ounces
Wing loading: 12.1 ounces per square
foot
Power: PSJ 3D 1000N brushless
outrunner motor (or equivalent), 35-amp
ESC, 20C 1500 mAh 3S Li-Poly battery
Construction: Balsa and light
plywood
Covering/finish: MonoKote or similar
36 MODEL AVIATION
05sig2.QXD 3/23/07 1:22 PM Page 36
Full-Size Plans Available—See Page 199
May 2007 37
05sig2.QXD 3/23/07 1:23 PM Page 37
38 MODEL AVIATION
Take your time and do a good job; this will
make all the difference in the SkyCruiser’s
finished appearance.
Install the main landing gear. The
assembly of the landing gear with wheel
pants is critical, to make sure the wheels
turn smoothly. The #6 screw goes through
the aluminum formed gear and then into the
wheel pant.
Notice that there is a #6 nut inside, then
the wheel, then two washers on the other
side of the wheel, which act as spacers.
When this assembly is put together in this
order, you can tighten the nut using curved
needle-nose pliers. Drive the final small
wood screw through the aluminum into the
wheel pant, to keep the wheel pant from
rotating.
Assemble the front gear by using two
washers as spacers on both sides of the
wheel inside the wheel pant, and then glue
the front wheel-pant retainer in place.
The wheel pants need to be painted—not
covered with MonoKote—and you should
do this before assembly. Leave an unpainted
place on the front wheel pant for the retainer
to be glued in later.
Install the front windshield and add the
3/8-inch radius by using your fingers to bend
it. Using heat is unnecessary for this step;
just roll the windshield with your fingers
until the large radius is formed. Do not roll
too hard or a tight radius will be formed
instead. It is a good idea to practice on a
scrap piece of acrylic before making the
actual windshield.
Covering and Painting: Cover the wing
first, but make sure to install the Y harness
and the aileron servos before you cover the
bottom of the wing. Make sure you cover
the entire bottom of the wing, including the
center-section; this will make it stronger.
The wing should have no twist or warp.
A bit of washout is okay, but make sure you
have the same amount on both sides and
don’t exceed 1/4 inch when measured at the
tips.
If the wing is twisted, have a helper turn
it back as necessary. While your aide is
holding the wing, reiron the MonoKote to
remove the wrinkles caused by the warping.
Cover the tail pieces and then the
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fuselage. Use clear MonoKote for the side
and rear windows, but don’t install the rear
window until the rudder and elevator servos
are hooked up to the pushrods; this window
opening is handy for accessing those servos.
The color scheme is perhaps the most
fun of the whole project. You can
personalize the airplane with the colors you
use or employ the one that I dreamed up.
Equipment Installation: Install the radio
receiver, the servos, the speed controller,
and then the battery, which can be placed in
the bottom of the fuselage or partly on top
of F4. Attach the radio receiver and battery
with nylon ties through the bottom of the
fuselage to get the CG correct, as shown on
the plans.
Drill a 2-inch-diameter hole in the
bottom of the fuselage to allow the battery
to be charged and for the connection from
the ESC to the battery when you are ready
to fly. You may want to add scrap balsa
pieces around the 2-inch hole for
reinforcement.
If the brushless motor turns backward
when you hook the three wires to the ESC,
exchange the connections on any two of the
wires and the motor will rotate correctly.
(Editor’s note: It is highly recommended
that you make the battery removable for
charging for safety’s sake.)
Flying: A prototype taking to the air for the
first time is a nervous occasion, and I am
glad I had my friend and accomplished test
pilot Dave Stuart to make the first flight for
me. I was taking video of the entire first
flight, so I had a good excuse not to make
it!
Dave was surprised by how quickly the
SkyCruiser lifted off from the runway at full
throttle (in approximately 20 feet). Once
airborne, he made some trim adjustments
and then tried a few maneuvers.
Elevator travel was excessive, so Dave
put the radio on low rate and proceeded to
do loops and aileron rolls. The model does
not roll very quickly, but it wasn’t designed
for quick rolls. He also performed a rudder
roll, during which the SkyCruiser lost quite
a bit of altitude. Dave’s comment was that
the model likes best to fly around at half
throttle, doing figure eights.
I was glad to see that the airplane can do
the aerial maneuvers, but this is not an
aerobatic aircraft and I think the design
purpose was met. Dave commented on the
model’s tendency to gain altitude at full
throttle instead of just speed.
I did make an angle-of-incidence
adjustment on the prototype by removing
the horizontal stabilizer and changing the
angle of incidence. This improved the flight
performance. I also readjusted the elevator
travel. The model plans reflect both
changes.
Many happy flights. MA
Clark Salisbury
671 E. 2160 N.
North Logan UT 84341
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